Communication systems that enable transmission of data to and from a user equipment, such as a mobile user terminal referred to as a mobile station are known. Data may be transmitted between the user equipment and another node, for example a server or another user terminal. A communication system typically operates in accordance with a given standard or specification which sets out what the various elements of the system are permitted to do and how that should be achieved. For example, it may be defined if the user, or more precisely, a user equipment or terminal is provided with a circuit switched service or a packet switched service or both. Communication protocols and/or parameters which shall be used for the connection are also typically defined. For example, the manner how communication shall be implemented between the user equipment and the elements of the communication network is typically based on a predefined communication protocol. In other words, a specific set of “rules” on which the communication can be based on needs to be defined to enable communication by means of the communication system.
Communication systems that provide mobility for the users thereof are known. The skilled person is aware of the basic principles of such mobile communication systems. A well known example is the public land mobile network (PLMN), known also as a cellular communication network. Another example is a mobile communication system that is at least partially based on use of communication satellites. Examples of mobile communication standards and/or specifications include, without limiting to these, specifications such as GSM (Global System for Mobile communications), GPRS (General Packet Radio Service), EDGE (Enhanced Data rate for GSM Evolution), AMPS (American Mobile Phone System), DAMPS (Digital AMPS), or 3rd generation (3G) communication systems such as the Universal Mobile Telecommunication System (UMTS), i-phone and so on.
User equipment (UE) may be served by various service areas (SA) of a communication system. In a typical case the service area can be defined as a certain area covered by at least one base transceiver station (BTS) that serves user equipment (UE) within the service area. The user equipment (UE) within one of the service areas may be controlled by one or several control entities. Examples of the control entities include radio network controllers such as a base station controller (BSC) of the GSM system and a radio network controller (RNC) of the 3rd generation (3G) systems. An access network controller is in communication with appropriate core network (CN) control entities. The core network entities may comprise control nodes such as a mobile switching center (MSC), a serving GPRS support node (SGSN) and various gateway nodes such as a gateway GPRS support node (GGSN) or gateway mobile switching center (GMSC). The network entities may also include nodes for storing information that associates with user equipment subscribing the network or visiting the network, such as appropriate home location registers (HLR) and visitor location registers (VLR). Depending on the implementation, a register node may be integrated with another network entity, or it may be a standalone network node.
A mobile communication system provides mobility for the user equipment in communication over a wireless interface with the network system. The user equipment is enabled to change from a service area to another service area. The change may occur e.g. when a user equipment moves i.e. roams from a cell to another cell. The user equipment may change even from a network system to another network system, as long as the user equipment is compatible with the standard of said other system.
Reception and/or transmission of data may be charged from the user equipment or other party involved in the data communication. Various possible schemes to implement the charging are known. For example, the subscription of the user equipment may be charged based on the capacity that was required for the transmission of data. The capacity may be measured as a volume of the data transmitted and/or received and/or based on time that was used for the data transmission. In some application the charge may also depend on the service the user equipment is using, and so on.
The charge may also depend on the location of the subscriber. For example, the operator of the communication system may have defined Service Areas (SAs) such that the subscriber is charged differently from similar services when located within different service areas. The charge may also depend on both the service the subscriber uses and his/hers location.
It is important that the charging is done correctly and fairly. An important part of the charging function is that the subscriber is not charged from any unsuccessful data transmissions. This unsuccessfully transmitted data will be referred to in the following as unsent data or ‘Unsuccessfully Transmitted Data Volume’. The ‘Unsuccessfully Transmitted Data Volume’ indicates the data volume (typically in octets) that is unsuccessfully transmitted over the radio interface via a radio access bearer (PAB). The data transmission may occur either in downlink (DL) or uplink (UL) direction.
If the subscriber moves from a service area to another service area where a different charge is levied for data transmission, the charging function should be able to charge the subscriber such that the charge includes only cost for the successful data transmissions rather than unsuccessful. That is, if the data cannot be sent while the user equipment is within the first service area but only when the user equipment is within a second service area, the bill should take this into account. However, the inventor has found that this is not possible in the prior art charging solutions.
FIG. 2a is a signalling flowchart in accordance with a prior art operation, and more particularly, illustrates the signalling flow in the context of the current 3G GPRS and/or UMTS systems. The prior art operation is such that when a subscriber changes from a service area to another, the radio network controller (RNC) generates a location report and sends it to a serving GPRS support node (SGSN).
The SGSN may ask for information regarding the Unsuccessfully Transmitted Data Volume from the radio network controller (RNC). This can be done by means of a Data Volume Request. However, the requests and responses may load substantially the interface and the network elements involved. Thus, if the SGSN wishes to receive information about possible unsent data from the RNC, it has to send a separate request for this information back to the RNC. If the subscriber moves rapidly, and thus several service area changes occurs within a short period of time, the SGSN and RNC become substantially heavily loaded. These location reports may occur at one SGSN at a rate of 10 million per a busy hour depending on the manner the network has been planned and the amount of subscriber movements. If the SGSN has to ask for information about unsent data from the RNC every time a location report arrives, the traffic load between the RNC and SGSN may also become substantially high. Therefore, if information about the unsent data is to be collected an easier way of doing so would be advantageous.
The prior art arrangements may not be able to provide exact information about the lost data in specific radio access areas such as in specific cells. A reason for this is that the RNC reports lost data only after being asked to do so.